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++++++++ Batteries -------------

Western civilisation hasbeen using lead acid batteries for more than a hundred years, longenough to understand them you would think- but there seem to be moretheories running around about batteries than there are brands ofbatteries !

Of course much of this is caused by claims and counter claims ofmanufacturers, so it is important to be aware of what is availableand what best suits your situation.

Lead Acid :
Plante, Tubular Positive, Traction,
Heavy Duty, Starting,

Nickel Cadmium :
Pocket Plate, Sintered Plate, FNC,

The most often used in Solar, Wind and Hydro Power.

Or as they are commonlytalked of, Telecom style batteries, have thick , almost pure leadplates and are designed for situations where they will only haveoccasional use, being a back- up style battery. In these situations,however, they will last many years. They are also quite efficient butcare needs to be taken when moving them as they are somewhat fragile.Formerly quite common in the Solar scene, they are now disappearingdue to a change in policy by Telecom, who used to sell them verycheaply.

The rising star in the world of Solar, are a version of lead acid batteries, but because of their unique construction they are not prone to the problems besetting all other varieties of lead acid batteries. For a start, the positive plate, being constructed of a tube filled with powder, can not fall to bits like other batteries- it is already in bits-, and also, because of the fine powder form, it is extremely resistant to sulphation, the curse of all other lead acid batteries. Indeed these Batteries don't mind being partly discharged for months at a time as long as they are being used and don't fall below about 30% of their capacity. They can actually be discharged to 20% of their capacity -

This is a general class ofbatteries often specified for such things as fork lifts, floorpolishers, golf buggies and the like. There is no one sort of batterythat fits this category, for instance Heavy Duty batteries, TubularPositive batteries and some Nickel Cadmium batteries could all bedescribed as Traction batteries; - it simply means that they can becycled deeply and at high rates of discharge. Generally speaking anybattery classified as Traction will perform better in a solarsituation than one which could not have that name.

This is a mixed bag, itincludes the normal car, truck, tractor, etc starting batteries, socalled deep cycle batteries, special sizes of batteries for buses,tanks, bulldozers etc. Despite what some people will tell you, someof these batteries will perform quite well in small Solar systems,and are often very cheap, and also quite efficient- more efficientthan the real thick plate deep cycle batteries. If one can avoidcycling them too deeply, they often last several years.

SinteredPlate Ni-Cads, are the variety mainly used as portable re-chargeablebatteries in torches, drills, computers, video cameras, toys, mobilephones, etc. They seem more expensive than conventional batteries,but when you consider that you can get a thousand cycles from them,they are cheap as chips.

PocketPlate Ni Cads, are the variety heretofore mainly used as emergency orstandby batteries in lifts, hospitals, large computer banks etc. Theyare chosen for their very long life, (25yrs claimed) low maintenance,and ability to be completely discharged without harm. Also somecompanies claim that Ni-Cads don't require a regulator .

The down sides to Pocket Plate Ni-Cads include high price, anefficiency factor of 1.4 (which means you have to put in 150% toretrieve 100% -lead acid batteries are approx. 1.22) a problem withelectrolyte contamination, which means you have to change theelectrolyte every 5 years, and while you can completely dischargethese batteries, you can only do it 100 times (approx).

This brings us to FIBRE Nickel CadmiumBatteries( F.N.C.), which overcome most of the problems of normal Ni-Cads,they have an efficiency of 1.2, dont suffer from electrolytepollution, don't die if repeatedly flattened, -they have an evenbetter cycle life than Ni-Cads, and a much better power to weightratio. However they cost even a little bit more than Ni-Cads, so forSolar they are a bit expensive, but ideal for electriccars.